Cleaning sheet, system and apparatus

ABSTRACT

The present invention provides a cleaning sheet that has an enhanced dirt, dust and/or debris pick-up and retention characteristics, which can be used in dry applications and/or wet applications. The cleaning sheet is prepared from a nonwoven web containing plurality of multicomponent multilobal filaments, wherein the multicomponent multilobal filaments have a plurality of raised lobal regions separated by depressed regions. The cleaning sheet also has voids between the plurality of multicomponent multilobal filaments which allow for enhanced dirt, dust and/or debris pick-up and retention. The nonwoven web can be a single layer or a layer of a multilayer laminate. The nonwoven web is optionally electret treated. Also disclosed is a cleaning implement and cleaning kit containing the cleaning sheet.

FIELD OF THE INVENTION

[0001] The present invention relates to cleaning sheets, implements forcleaning surfaces and a method of cleaning surfaces. More particularlythe present invention relates to disposable cleaning sheets, implementsfor use in wet surface-cleaning applications or dry surface cleaningapplications and a method of cleaning surfaces using the disposablecleaning sheets and cleaning implements of the present invention.

BACKGROUND OF THE INVENTION

[0002] Disposable cleaning sheets have heretofore been used inconnection with cleaning tools such as mops and brushes. As an example,U.S. Pat. No. 5,461,749 to Ahlberg et al. discloses a floor mop orfabric for picking-up and retaining dust. The cleaning fabric can beattached to a mop head thereby allowing the mop to be used in as a“duster”, i.e. a tool or fabric for picking-up dust and otherparticulate matter. Once the cleaning fabric is soiled, it can beremoved from the mop head and a new, clean sheet placed therein. Asimilar product is disclosed in published PCT Application WO97/04701 toSuzuki et al. This publication discloses a flat bag-like cleaning clothhaving an insertion space. The head portion of a handle is insertedwithin the insertion space to form a cleaning apparatus for use as aduster. As a further example, published PCT Application WO98/52548discloses a sheet material having a macroscopically three-dimensionalstructure suitable for use a duster in conjunction with a handle orother cleaning tool.

[0003] In addition, U.S. Pat. No. 4,823,427 to Gibbs et al. teaches theuse of an absorbent elastic mop head cover that can be secured to themop head without fasteners. The elastic mop head cover can comprise ameltblown fiber fabric and, in one embodiment, can include absorbentmaterials such as wood pulp or synthetic staple fibers in order toincrease the water or oil absorbency of the fabric. While Gibbs providesa durable cleaning sheet suitable for use in wet and/or dry cleaningapplications, cleaning sheets having improved durability and an improvedcapacity to pick up larger and/or coarser particulate matter aredesirable. Thus, there exists a need for cleaning sheets and implementssuitable for use in dry or wet surface-cleaning applications which arehighly durable, capable of absorbing liquids and further which are alsocapable of picking up dirt and large particulate matter. Still further,there exists a need for such a cleaning sheet that is also sufficientlyinexpensive so as to comprise a disposable product.

SUMMARY OF THE INVENTION

[0004] The present invention provides a cleaning sheet that has anenhanced dirt, dust and/or debris pick-up and retention characteristics,which can be used in dry applications and/or wet applications.

[0005] It has been discovered, as a result of the present invention, acleaning sheet comprising a nonwoven web comprising a plurality ofmulticomponent multilobal filaments, wherein the multicomponentmultilobal filaments comprises a plurality of raised lobal regionsseparated by depressed regions and the nonwoven web comprises voidsbetween the plurality of multicomponent multilobal filaments hasenhanced dirt, dust and/or debris pick-up and retention.

[0006] In a further aspect of the present invention, it has beendiscovered that a cleaning sheet comprising a nonwoven web comprising amixture of a plurality of multicomponent multilobal filaments, and aplurality of monolobal filaments, wherein the multicomponent multilobalfilaments comprises a plurality of raised lobal regions separated bydepressed regions and the nonwoven web comprises voids between theplurality of multicomponent filaments and/or the monolobal filaments hasenhanced dirt, dust and/or debris pick-up and retention.

[0007] Further discovered is a multilayered cleaning sheet comprising afirst layer comprising a plurality of multicomponent multilobalfilaments, wherein the multicomponent multilobal filaments comprises aplurality of raised lobal regions separated by depressed regions and thelayer comprises voids between the plurality of multicomponent filaments,and a second layer comprising monolobal filaments also has enhanceddirt, dust and/or debris pick-up and retention.

[0008] The present invention also relates to a cleaning implementcomprising a handle; a head; and a removable cleaning sheet; wherein thehead is connected to the handle, and the removable cleaning sheet isremovably attached to the head. The cleaning sheet comprises a nonwovenweb comprising a plurality of multicomponent multilobal filaments,wherein each of the filaments comprises a plurality of raised lobalregions separated by depressed regions and the nonwoven web comprisesvoids between the plurality of multicomponent filaments which allow forenhanced dirt, dust and/or debris pick-up and retention.

[0009] A further aspect of the present invention relates a method ofcleaning a surface comprising contacting and wiping the surface with thecleaning sheet of the present invention.

[0010] The present invention also relates to a kit containing thecleaning implement of the present invention and a plurality of thecleaning sheets of the present invention.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0011]FIG. 1 illustrates cross-section shapes of several differentmultilobal fibers suitable for the nonwoven web cleaning sheet of thepresent invention.

[0012]FIG. 2 illustrates one process for producing the nonwoven web usedin the cleaning sheet of the present invention.

[0013]FIG. 3 illustrates a cleaning implement of the present invention.

DEFINITIONS

[0014] As used herein, the term “cleaning sheet” or “wiping sheet” isintended to include any web which is used to clean an article or asurface. Examples of cleaning sheets include, but are not limited to,webs of material containing a single sheet of material which is used toclean a surface by hand or a sheet of material which can be attached toa cleaning implement, such as a floor mop or a hand held cleaning tool,such as a duster.

[0015] As used herein, the term “fiber” includes both staple fibers,i.e., fibers which have a defined length between about 2 and about 20mm, fibers longer than staple fiber but are not continuous, andcontinuous fibers, which are sometimes called “continuous filaments” orsimply “filaments”. The method in which the fiber is prepared willdetermine if the fiber is a staple fiber or a continuous filament.

[0016] As used herein, the term “nonwoven web” means a web having astructure of individual fibers or threads which are interlaid, but notin an identifiable manner as in a knitted web. Nonwoven webs have beenformed from many processes, such as, for example, meltblowing processes,spunbonding processes, and bonded carded web processes. The basis weightof nonwoven webs is usually expressed in ounces of material per squareyard (osy) or grams per square meter (gsm) and the fiber diametersuseful are usually expressed in microns, or in the case of staplefibers, denier. It is noted that to convert from osy to gsm, multiplyosy by 33.91.

[0017] The term “denier” is defined as grams per 9000 meters of a fiber.For a fiber having circular cross-section, denier may be calculated asfiber diameter in microns squared, multiplied by the density ingrams/cc, multiplied by 0.00707. A lower denier indicates a finer fiberand a higher denier indicates a thicker or heavier fiber. Outside theUnited States the unit of measurement is more commonly the “tex,” whichis defined as the grams per kilometer of fiber. Tex may be calculated asdenier/9. The “mean fiber denier” is the sum of the deniers for eachfiber, divided by the number of fibers.

[0018] As used herein, the term “bulk density” refers to the weight of amaterial per unit of volume and is generally expressed in units of massper unit bulk volume (e.g., grams per cubic centimeter).

[0019] As used herein, the term “spunbonded fibers” refers to fiberswhich are formed by extruding molten thermoplastic material as filamentsfrom a plurality of fine, usually circular capillaries of a spinneretwith the diameter of the extruded filaments then being rapidly reducedas by, for example, U.S. Pat. No 4,340,563 to Appel et al., and U.S.Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 toMatsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S.Pat. No. 3,502,763 to Hartman; U.S. Pat. No. 3,542,615 to Dobo et al.;and U.S. Pat. No. 5,382,400 to Pike et al.; the entire content of eachis incorporated herein by reference. Spunbond fibers are generally nottacky when they are deposited onto a collecting surface. Spunbond fibersare generally continuous and have average diameters (from a sample of atleast 10) larger than 7 microns to about 50 or 60 microns, often,between about 15 and 25 microns.

[0020] As used herein, the term “meltblown fibers” means fibers formedby extruding a molten thermoplastic material through a plurality offine, usually circular, die capillaries as molten threads or filamentsinto converging high velocity, usually hot, gas (e.g. air) streams whichattenuate the filaments of molten thermoplastic material to reduce theirdiameter, which may be to microfiber diameter. Thereafter, the meltblownfibers are carried by the high velocity gas stream and are deposited ona collecting surface to form a web of randomly dispersed meltblownfibers. Such a process is disclosed, for example, in U.S. Pat. No.3,849,241. Meltblown fibers are microfibers, which may be continuous ordiscontinuous, and are generally smaller than 10 microns in averagediameter, and are generally tacky when deposited onto a collectingsurface.

[0021] As used herein, the term “polymer” generally includes, but is notlimited to, homopolymers, copolymers, such as for example, block, graft,random and alternating copolymers, terpolymers, etc. and blends andmodifications thereof. Furthermore, unless otherwise specificallylimited, the term “polymer” shall include all possible geometricalconfigurations of the molecule. These configurations include, but arenot limited to isotactic, syndiotactic and random symmetries.

[0022] As used herein, the term “conjugate fibers” refers to fibers orfilaments which have been formed from at least two polymers extrudedfrom separate extruders but spun together to form one fiber. Conjugatefibers are also sometimes referred to as “multicomponent” or“bicomponent” fibers or filaments. The term “bicomponent” means thatthere are two polymeric components making-up the fibers. The polymersare usually different from each other though conjugate fibers may beprepared from the same polymer, but the polymers are different from oneanother in some physical property, such as, for example, melting pointor the softening point. The polymers are arranged in substantiallyconstantly positioned distinct zones across the cross-section of themulticomponent fibers or filaments and extend continuously along thelength of the multicomponent fibers or filaments. The configuration ofsuch a multicomponent fiber may be, for example, a sheath/corearrangement, wherein one polymer is surrounded by another, aside-by-side arrangement, a pie arrangement or an “islands-in-the-sea”arrangement. Multicomponent fibers are taught in U.S. Pat. No. 5,108,820to Kaneko et al., U.S. Pat. No. 5,336,552 to Strack et al., and U.S.Pat. No. 5,382,400 to Pike et al., the entire content of each isincorporated herein by reference. For two component fibers or filaments,the polymers may be present in ratios of 75/25, 50/50, 25/75 or anyother desired ratios.

[0023] As used herein, the term “multiconstituent fibers” refers tofibers which have been formed from at least two polymers extruded fromthe same extruder as a blend or mixture. Multiconstituent fibers do nothave the various polymer components arranged in relatively constantlypositioned distinct zones across the cross-sectional area of the fiberand the various polymers are usually not continuous along the entirelength of the fiber, instead usually forming fibrils or protofibrilswhich start and end at random.

[0024] As used herein, the term “hot air knife” or HAK means a processof preliminarily bonding a just produced microfiber web, particularlyspunbond, in order to give it sufficient integrity, i.e. increase thestiffness of the web, for further processing, but does not mean therelatively strong bonding of secondary bonding processes likethrough-air bonding, thermal bonding and ultrasonic bonding. A hot airknife is a device which focuses a stream of heated air at a very highflow rate, generally from about 1000 to about 10,000 feet per minute(fpm) (305 to 3050 meters per minute), or more particularly from about3000 to 6000 feet per minute (915 to 1830 meters per minute) directed atthe nonwoven web immediately after the nonwoven web formation. The airtemperature is usually in the range of the melting point of at least oneof the polymers used in the web, generally between about 200° and 550°F. (93° and 290° C.) for the thermoplastic polymers commonly used inspunbonding. However, the temperature of the air must be adjustedaccordingly for the particular polymers used to prepare the nonwovenweb. The control of air temperature, velocity, pressure, volume andother factors helps avoid damage to the web while increasing itsintegrity. The HAK's focused stream of air is arranged and directed byat least one slot of about ⅛ to 1 inches (3 to 25 mm) in width,particularly about ⅜ inch (9.4 mm), serving as the exit for the heatedair towards the web, with the slot running in a substantiallycross-machine direction over substantially the entire width of the web.In other embodiments, there may be a plurality of slots arranged next toeach other or separated by a slight gap. At least one slot is usually,though not essentially, continuous, and may be comprised of, forexample, closely spaced holes. The HAK has a plenum to distribute andcontain the heated air prior to its exiting the slot. The plenumpressure of the HAK is usually between about 1.0 and 12.0 inches ofwater (2 to 22 mmHg), and the HAK is positioned between about 0.25 and10 inches and more preferably 0.75 to 3.0 inches (19 to 76 mm) above theforming wire. In a particular embodiment the HAK plenum's crosssectional area for cross-directional flow (i.e. the plenum crosssectional area in the machine direction) is at least twice the totalslot exit area. Since the forming wire onto which spunbond polymer isformed generally moves at a high rate of speed, the time of exposure ofany particular part of the web to the air discharged from the hot airknife is less a tenth of a second and generally about a hundredth of asecond in contrast with the through-air bonding process which has a muchlarger dwell time. The HAK process has a great range of variability andcontrollability of many factors such as air temperature, velocity,pressure, volume, slot or hole arrangement and size, and the distancefrom the HAK plenum to the web. The HAK is further described in U.S.Pat. No. 5,707,468 to Arnold et al., the entire contents of which isincorporated by reference.

[0025] As used herein, through-air bonding or “TAB” means a process ofbonding a nonwoven fiber web in which air, which is sufficiently hot tomelt one of the polymers of which the fibers of the web are made, isforced through the web. The air velocity is between 100 and 500 feet perminute and the dwell time may be as long as 10 seconds. The melting andresolidification of the polymer provides the bonding. Through-airbonding has relatively restricted variability and since through-airbonding requires the melting of at least one component to accomplishbonding, it is generally restricted to webs with two components likemulticomponent fibers or those which include an adhesive. In thethrough-air bonder, air having a temperature above the meltingtemperature of one component and below the melting temperature ofanother component is directed from a surrounding hood, through the web,and into a perforated roller supporting the web. Alternatively, thethrough-air bonder may be a flat arrangement wherein the air is directedvertically downward onto the web. The operating conditions of the twoconfigurations are similar, the primary difference being the geometry ofthe web during bonding. The hot air melts the lower melting polymercomponent and thereby forms bonds between the filaments to integrate theweb.

[0026] As used herein “thermal point bonded” means bonding one or morefabrics with a pattern of discrete bond points. As an example, thermalpoint bonding often involves passing a fabric or web of fibers to bebonded at a nip between a pair of heated bonding calender rolls. One ofthe bonding rolls is usually, though not always, patterned in some wayso that the entire fabric is not bonded across its entire surface, andthe second or anvil roll is usually a smooth surface. As a result,various patterns for calender rolls have been developed for functionalas well as aesthetic reasons. One example of a pattern has points and isthe Hansen Pennings or “H&P” pattern with about a 30% bond area withabout 200 bonds/square inch as taught in U.S. Pat. No. 3,855,046 toHansen and Pennings. The H&P pattern has square point or pin bondingareas wherein each pin has a side dimension of 0.038 inches (0.965 mm),a spacing of 0.070 inches (1.778 mm) between pins, and a depth ofbonding of 0.023 inches (0.584 mm). The resulting pattern has a bondedarea of about 29.5%. Another typical point bonding pattern is theexpanded Hansen Pennings or “EHP” bond pattern which produces a 15% bondarea with a square pin having a side dimension of 0.037 inches (0.94mm), a pin spacing of 0.097 inches (2.464 mm) and a depth of 0.039inches (0.991 mm). Another typical point bonding pattern designated“714” has square pin bonding areas wherein each pin has a side dimensionof 0.023 inches, a spacing of 0.062 inches (1.575 mm) between pins, anda depth of bonding of 0.033 inches (0.838 mm). The resulting pattern hasa bonded area of about 15%. Yet another common pattern is the C-Starpattern which has a bond area of about 16.9%. The C-Star pattern has across-directional bar or “corduroy” design interrupted by shootingstars. Other common patterns include a diamond pattern with repeatingand slightly offset diamonds with about a 16% bond area and a wire weavepattern, having generally alternating perpendicular segments, with abouta 19% bond area. Typically, the percent bonding area varies from around10% to around 30% of the area of the fabric laminate web. Point bondingmay be used to hold the layers of a laminate together and/or to impartintegrity to individual layers by bonding filaments and/or fibers withinthe web.

[0027] As used herein “pattern unbonded” or interchangeably “pointunbonded” or “PUB”, means a fabric pattern having continuous bondedareas defining a plurality of discrete unbonded areas. The fibers orfilaments within the discrete unbonded areas are dimensionallystabilized by the continuous bonded areas that encircle or surround eachunbonded area, such that no support or backing layer of film or adhesiveis required. The unbonded areas are specifically designed to affordspaces between fibers or filaments within the unbonded areas. A suitableprocess for forming the pattern-unbonded nonwoven material includesproviding a nonwoven fabric or web, providing opposedly positioned firstand second calender rolls and defining a nip there between, with atleast one of said rolls being heated and having a bonding pattern on itsoutermost surface comprising a continuous pattern of land areas defininga plurality of discrete openings, apertures or holes, and passing thenonwoven fabric or web within the nip formed by said rolls. Each of theopenings in said roll or rolls defined by the continuous land areasforms a discrete unbonded area in at least one surface of the nonwovenfabric or web in which the fibers or filaments of the web aresubstantially or completely unbonded. Stated alternatively, thecontinuous pattern of land areas in said roll or rolls forms acontinuous pattern of bonded areas that define a plurality of discreteunbonded areas on at least one surface of said nonwoven fabric or web.The PUB pattern is further described in U.S. Pat. No. 5,858,515 toStokes et al, the entire contents of which are hereby incorporated byreference.

[0028] As used herein, the term “debris” means items which typicallyneed removal during a cleaning process. This term is intended toinclude, but is not limited to, hair (both human and pet), dandruff(both human and pet), food particles, e.g. crumbs from bread, cakescookies and the like, grass, dirt, defoliated skin, and other suchitems.

Detailed Description

[0029] The inventors of the present invention have discovered thatnonwoven webs formed from multicomponent, multilobal shaped fibers havean enhanced dirt, dust and/or debris pickup and retention within thenonwoven web. Furthermore, the multicomponent, multilobal shaped fibersare also shaped in ways meant to enhance liquid retention. Theseproperties provide for a cleaning sheet which can be used in both dryand wet applications, which provide enhance and effective dirt, dustand/or debris pickup and retention, while, at the same time, can alsoprovide absorbency of liquids. The multicomponent, multilobal shapedfibers have “lobes” separated by depressed regions which allow thenonwoven web to absorb liquids and hold the absorbed liquids in placewithin the nonwoven structure. Tips of the multicomponent, multilobalshaped fibers increase surface area which provides for enhance surfacecontact, which in turn provides for the enhanced dirt, dust and/ordebris pickup of the cleaning sheet. In addition, the multilobal shapeof the fibers also creates voids within the nonwoven web structure whichallows for dirt, dust and/or debris retention within the nonwoven web.

[0030] The shaped fibers of the present invention may be spunbond fibersmade from at least two polymers as multicomponent fibers and have atleast one lobe capable of holding liquid. Multicomponent fibers may besplit, crimped and through-air bonded among many other properties andbonding options. Combining the advantages of the liquid and particlepick-up and retention of multilobal fibers with the processingadvantages of multicomponent fiber results in a nonwoven web which hashighly desirable properties needed in cleaning sheets. In addition, thefibers of the present invention have improved processibility and canprovide a myriad of different nonwoven webs having properties which canbe tailored to the needs of the end user.

[0031] The spunbond process generally uses a hopper which suppliespolymer to a heated extruder. The extruder supplies melted polymer to aspinneret where the polymer is fiberized as it passes through fineopenings arranged in one or more rows in the spinneret, forming acurtain of filaments. The filaments are usually quenched with air at alow pressure, drawn, usually pneumatically and deposited on a movingforaminous mat, belt or “forming wire” to form the nonwoven web.Polymers useful in the spunbond process commonly have a process melttemperature of between about 400° F. to about 610° F. (200° C. to 320°C.).

[0032] The fibers produced in the spunbond process are usually in therange of from about 5 to about 50 microns in average diameter, dependingon process conditions and the desired end use for the webs to beproduced from such fibers. For example, increasing the polymer molecularweight or decreasing the processing temperature results in largerdiameter fibers. Changes in the quench fluid temperature and pneumaticdraw pressure can also affect fiber diameter. The fibers used in thepractice of this invention usually have average diameters in the rangeof from about 7 to about 35 microns, more particularly from about 15 toabout 25 microns.

[0033] The fibers used to produce the web of this invention aremulticomponent fibers. As these multicomponent fibers are produced andcooled, the differing coefficients of expansion of the polymers cancause these fibers to bend and ultimately to crimp, somewhat akin to theaction of the bimetallic strip in a conventional room thermostat.Crimped fibers are described in U.S. Pat. No. 5,382,400 wherein fibersare crimped with the same air as is used to draw them. Sufficiently warmdrawing air activates the latent helical crimp of the fibers as thefibers are produced and before they are deposited on the forming wire.Crimped fibers have an advantage over uncrimped fibers in that theyproduce a more bulky web, thereby increasing the void spacing within thenonwoven web. Larger void spacing is a desirable characteristic forcleaning sheets, since the larger voids will allow for the pickup andretention of larger particles of dirt, dust and/or debris. Therefore,crimped fibers are somewhat more desirable than uncrimped fibers incleaning sheets. Additionally, the degree of crimp can be controlled bycontrolling the temperature of the drawing air, thereby providing amechanism for controlling the web density. Generally, a higher airtemperature produces a higher number of crimps. This allows one tochange the resulting bulk density, and void size distribution of theresulting cleaning sheet by simply adjusting the temperature of the airin the fiber draw unit.

[0034] In the present invention, the nonwoven web cleaning sheets willtypically have a bulk density of about 0.01 to about 0.2 g/cm³.Preferably, the cleaning sheets with have a bulk density of about 0.015to about 0.075 g/cm³ and ideally about 0.02 to about 0.05 g/cm³.

[0035] The nonwoven web cleaning sheets of the present invention mayhave basis weights ranging from about 0.25 osy (8.5 gsm) to about 25 osy(850 gsm). The actual basis weight of the nonwoven material is dependentof the final use of the cleaning sheet. It is desirable that the basisweight be in the range from about 0.5 osy (17 gsm) to about 10 osy (340gsm), and preferably about 1.0 osy (34 gsm) to about 5 osy (170 gsm),for many applications.

[0036] The multicomponent, multilobal shape of the fibers used in thepractice of this invention must provide areas in which dirt, dust and/ordebris can be retained and/or where liquids may be retained. Preferredshapes are those described in U.S. Pat. Nos. 5,069,970 and 5,057,368 toLargman et al., assigned to Allied Signal, Inc., hereby incorporated byreference in their entirety, which describe fibers with unconventionalshapes. In addition, shaped fibers are also described in U.S. Pat. Nos.5,314,743, 5,342,336 and 5,458,963 to Meirowitz et al., herebyincorporated by reference in their entirety. None of these patents,however, suggest multicomponent fibers or the unique advantages of suchfibers in crimping, varying web pore size or bonding and which areimportant factors determining the usefulness of such fibers when used tocreate a nonwoven web cleaning sheet. Multicomponent shaped fibers areknown in the art and have been used in filter fabrics as is shown inU.S. Pat. No. 5,707,735 to Midkiff et al, which is also herebyincorporated by reference in its entirety. Fibers having the shapes andconfigurations of the '735 patent may also be used in the presentinvention. Generally, the multilobal fibers of the present in inventionwill have between 2 and 10 lobes, but preferably have between 2 and 5lobes. Other examples of multicomponent, shaped fibers which can be usedin the present invention are shown in FIG. 1.

[0037] Referring to FIG. 1(a), a bilobal bicomponent nonwoven fiber 100is shown in cross-section. The fiber 100 has two lobes 112 and 114, anddepressed regions 116 and 118 on both sides of fiber 110 between thelobes. A boundary line 119 indicates the interface between a polymercomponent forming one of the lobes 112 and 114, and a polymer componentforming the other lobe. The polymer components of the fiber are arrangedside-by-side.

[0038]FIG. 1(b) illustrates, in cross-section, a trilobal bicomponentnonwoven fiber 120 in which the three lobes 122, 124 and 126 arepositioned at right angles to each other. A depressed region 123 islocated between the lobes 122 and 124. A depressed region 125 is locatedbetween the lobes 122 and 126. It should be apparent from FIG. 1(b), forinstance, that the term “depressed region” refers to a region which isconcave with respect to a straight line drawn tangential to the twoadjacent lobes. In FIG. 1(b), a straight line 127 can be drawntangential to adjacent lobes 122 and 124, with concave portion 123underneath the straight line. A similar straight line can be drawntangential to adjacent lobes 122 and 126. However, no concave regionexists with respect to a straight line drawn tangential to adjacentlobes 124 and 126. In FIG. 1(b), the dividing line 129 represents aninterface between a polymer component forming half of the fiber, and apolymer component forming the other half of the fiber. Again, thepolymer components of the fiber are arranged in a side-by-sideconfiguration.

[0039]FIG. 1(c) illustrates, in cross-section, a trilobal bicomponentnonwoven fiber 130 in which the three lobes 132, 134 and 136 arepositioned at 60-degree angles to each other. A depressed region 133 islocated between lobes 132 and 134. A depressed region 135 is locatedbetween lobes 132 and 136. A depressed region 137 is located betweenlobes 134 and 136. A dividing line 139 represents an interface between apolymer forming half of the fiber 130, and a polymer forming the otherhalf. Again, the fiber 130 has a side-by-side distribution of thepolymer components.

[0040]FIG. 1(d) illustrates, in cross-section, a quadrilobal bicomponentfiber 140 in which the four lobes 142, 144, 146 and 148 are arranged ina star-like configuration. Depressed regions 141, 143, 145 and 147 areformed between each pair of adjacent lobes. A circular dividing line 149represents an interface between the polymer components. In thisinstance, the bicomponent fiber has a sheath-core configuration with onepolymer forming the core and the other polymer forming the sheath.

[0041]FIG. 1(e) illustrates, in cross-section, a quadrilobal bicomponentfiber 150 in which the four lobes 152, 154, 156 and 158 are arranged ina cross configuration. Depressed regions 151, 153, 155 and 157 areformed between each pair of adjacent lobes. Dividing line 159 representsthe interface between polymer components, which are arranged in aside-by-side configuration.

[0042]FIG. 1(f) illustrates, in cross-section, a pentalobal bicomponentfiber 160 having five lobes 162, 164, 166, 168 and 170 arranged atapproximately 72-degree angles to each other. Depressed regions 161,163, 165, 167 and 169 are formed between each pair of adjacent lobes.Dividing line 171 represents the interface between the polymercomponents which are arranged in a side-by-side configuration.

[0043]FIG. 1(g) illustrates, in cross-section, a quadrilobal bicomponentfiber 180 in which the four lobes 182, 184, 186 and 188 are arranged ina cross configuration. Depressed regions 181, 183, 185 and 187 areformed between each pair of adjacent lobes. Dividing lines 189represents the interface between polymer components, which are arrangedin a sheath/core configuration.

[0044]FIG. 1(h) illustrates, in cross-section, a pentalobal bicomponentfiber 200 having five lobes 202, 204, 206, 208 and 210 arranged atapproximately 72-degree angles to each other. Depressed regions 201,203, 205, 207 and 209 are formed between each pair of adjacent lobes.Dividing line 211 represents the interface between the polymercomponents which are arranged in a sheath/core configuration.

[0045] It is pointed out that the shape of the fibers which can be usedin the present invention are not limited to the specific shape orconfigurations shown in FIG. 1. Other shapes and configurations of themulticomponent, multilobal shaped fibers can, so long as the resultingnonwoven web has an ability to pick-up and retain dirt, dust and/ordebris and/or to absorb and retain fluids.

[0046] The polymers suitable for the present invention includepolyolefins, polyesters, polyamides, polycarbonates, polyurethanes,polyvinylchloride, polytetrafluoroethylene, polystyrene, polyethyleneterephathalate, biodegradable polymers such as polylactic acid andcopolymers and blends thereof Suitable polyolefins include polyethylene,e.g., high density polyethylene, medium density polyethylene, lowdensity polyethylene and linear low density polyethylene; polypropylene,e.g., isotactic polypropylene, syndiotactic polypropylene, blends ofisotactic polypropylene and atactic polypropylene, and blends thereof;polybutylene, e.g., poly(1-butene) and poly(2-butene); polypentene,e.g., poly(1-pentene) and poly(2-pentene); poly(3-methyl-1-pentene);poly(4-methyl 1-pentene); and copolymers and blends thereof. Suitablecopolymers include random and block copolymers prepared from two or moredifferent unsaturated olefin monomers, such as ethylene/propylene andethylene/butylene copolymers. Suitable polyamides include nylon 6, nylon6/6, nylon 4/6, nylon 11, nylon 12, nylon 6/10, nylon 6/12, nylon 12/12,copolymers of caprolactam and alkylene oxide diamine, and the like, aswell as blends and copolymers thereof. Suitable polyesters includepolyethylene terephthalate, polytrimethylene terephthalate, polybutyleneterephthalate, polytetramethylene terephthalate,polycyclohexylene-1,4-dimethylene terephthalate, and isophthalatecopolymers thereof, as well as blends thereof.

[0047] Many polyolefins are available for fiber production, for examplepolyethylenes such as Dow Chemical's ASPUN 6811A linear low-densitypolyethylene, 2553 LLDPE and 25355 and 12350 high density polyethyleneare such suitable polymers. The polyethylenes have melt flow rates ing/10 min. at 190° F. and a load of 2.16 kg, of about 26, 40, 25 and 12,respectively. Fiber forming polypropylenes include Exxon ChemicalCompany's ESCORENE PD3445 polypropylene. Many other polyolefins arecommercially available and generally can be used in the presentinvention. The particularly preferred polyolefins are polypropylene andpolyethylene.

[0048] Examples of polyamides and their methods of synthesis may befound in “Polymer Resins” by Don E. Floyd (Library of Congress Catalognumber 66-20811, Reinhold Publishing, N.Y., 1966). Particularlycommercially useful polyamides are nylon 6, nylon-6,6, nylon-11 andnylon-12. These polyamides are available from a number of sources suchas Custom Resins, Nyltech, among others. In addition, a compatibletackifying resin may be added to the extrudable compositions describedabove to provide tackified materials that autogenously bond or whichrequire heat for bonding. Any tackifier resin can be used which iscompatible with the polymers and can withstand the high processing(e.g., extrusion) temperatures. If the polymer is blended withprocessing aids such as, for example, polyolefins or extending oils, thetackifier resin should also be compatible with those processing aids.Generally, hydrogenated hydrocarbon resins are preferred tackifyingresins, because of their better temperature stability. REGALREZ® andARKON® P series tackifiers are examples of hydrogenated hydrocarbonresins. ZONATAC® 501 lite is an example of a terpene hydrocarbon.REGALREZ® hydrocarbon resins are available from Hercules Incorporated.ARKON® series resins are available from Arakawa Chemical (USA)Incorporated. The tackifying resins such as disclosed in U.S. Pat. No.4,787,699, hereby incorporated by reference, are suitable. Othertackifying resins which are compatible with the other components of thecomposition and can withstand the high processing temperatures, can alsobe used.

[0049] In addition, the lobes may be made from particular polymers whichare hydrophilic or which may be treated for hydrophilicity which willenhance the ability of the nonwoven web to absorb aqueous liquids.

[0050] The polymers used to make the nonwoven web may contain additives,such as surfactants or slip agents, to aid in the sliding of thesensitive surface against the nonwoven material. Other additives, suchas pigments, dyes, processing aids and the like can be added to thepolymer prior to fiber formation, provided that the additives do notadversely affect the ability of the nonwoven web to pickup and retaindirt, dust and/or debris and/or the ability of the nonwoven web toabsorb liquids. Ferroelectric materials, such as those disclosed in U.S.Pat. No. 6,162,535 to Turkevich et al, assigned to the assignee of thisinvention, and is incorporated in its entirety by reference, may also beadded to fibers. In addition, other polymeric additives, such as maleicanhydride telomers may also be added, for example to provide electretstability.

[0051] It is desirable that the particular polymers used for thedifferent components of the fibers in the practice of the invention havemelting points different from one another. This is important not only inproducing crimped fibers but also when through-air bonding is used asthe bonding technique, wherein the lower melting polymer bonds thefibers together to form the fabric or web. It is desirable that thelower melting point polymers makes up at least a portion of the outerregion of the fibers. More particularly, the lower melting componentshould be located in an outer portion of the fiber so that it comes incontact with other fibers. For example, in a sheath/core fiberconfiguration, the lower melting point polymer component should belocated in the sheath portion. In a side-by-side configuration, thelower melting point polymer will inherently be located on an outerportion of the fiber.

[0052] The proportion of higher and lower melting polymers in themulticomponent, multilobal fibers can range between about 10-90% byweight higher melting polymer and 10-90% lower melting polymer. Inpractice, only so much lower melting polymer is needed as willfacilitate bonding between the fibers. Thus, a suitable fibercomposition may contain about 40-80% by weight higher melting polymerand about 20-60% by weight lower melting polymer, desirably about 50-75%by weight higher melting polymer and about 25-50% by weight lowermelting polymer.

[0053] In a preferred embodiment, a first polymer, which is the lowermelting point polymer is polyethylene and the higher melting pointpolymer is polypropylene. This embodiment is preferred from thestandpoint of cost and resulting properties of the cleaning sheet.

[0054] After the fibers are formed and deposited on the forming wire andcreate the web of this invention, the web may be passed through a hotair knife or HAK to very slightly consolidate the web and provide theweb with enough integrity for further processing. After deposition butbefore HAK treatment, the fiber web has low stiffness which makes itsdifficult, if not impossible, to successfully convert on commerciallyavailable converting equipment commonly used to the final use. Theapplication of the HAK allows forming a web of fibers to deliver highstiffness by melting only a portion of the lower melting component inthe web, preferably only that lower melting component on the side facingthe HAK air, in a pre- or primary bonding step. This HAK step creates azone of pre-bonded fibers located on one side of the web which thenundergo a second melting when exposed to through-air bonding or bondingwith a heated bonding roll, such as a roll which will impart a PUBpattern to the nonwoven web or a roll which imparts a thermal pointbonded pattern to the web. The exposure of this zone to at least twoheating and melting cycles is believed to create a zone of highstiffness in the web from the crystallization of the polymer, however,since the zone is comprised of a small percentage of the total web, theeffect on bulk density of the web is minimized. This differs from thecommonly used method of increasing the integrity of a web known ascompaction rolls since, while compaction rolls increase the stiffness ofa web, the compaction rolls also increase the bulk density of the web.It is noted, however, that while compaction rolls may be used in thepractice of this invention, the HAK is generally preferred since the HAKdoes not reduce the void spacing of the web while compaction rolls willreduce the void spacing. After treatment with the HAK, the web issufficiently cohesive to move it to the next step of production; thesecondary bonding step. Any secondary bonding known to those skilled inthe art can be used.

[0055] The secondary bonding procedure which may be used in the practiceof this invention is preferably through-air bonding because it does notappreciably reduce web void (pore) size. When used with HAK pre-bonding,through-air bonding very effectively produces high stiffness in the websince it provides a second heating of the polymer previously heated bythe HAK and provides sufficient heat to bond fibers not bonded by theHAK. This creates bonds at almost every fiber crossover point, therebyrestricting movement of the majority of the fibers of the web.

[0056] Other secondary bonding methods can be used without limitation.Examples of other secondary bonding methods include PUB bonding andthermal point bonding. In the PUB pattern, a continuous bond area isformed with a plurality of discrete unbonded areas. Thermal pointbonding by contrast results has discrete bonding points, and acontinuous unbonded area.

[0057] Through-air bonding is preferred secondary bonding because itdoes not appreciably reduce void size when compared, for example, tothermal point bonding. Through-air bonding creates small bonds at almostevery fiber crossover point, minimally effecting the void size withinthe nonwoven web structure. Thermal point bonding by contrast results incomparatively large bonds at discrete points, compressing the web inareas around the bond points which decreases the void size at or nearthe bond points.

[0058] After the secondary bonding, the nonwoven web may be electrettreated. Electret treatment further increases ability of the nonwovenweb to pick-up and retain dirt, dust and/or debris by drawing the dirt,dust and/or debris into the nonwoven web by virtue of their electricalcharge. Electret treatment can be carried out by a number of differenttechniques. One technique is described in U.S. Pat. No. 5,401,446 toTsai et al. assigned to the University of Tennessee Research Corporationand incorporated herein by reference in its entirety. Tsai describes aprocess whereby a web or film is sequentially subjected to a series ofelectric fields such that adjacent electric fields have substantiallyopposite polarities with respect to each other. Thus, one side of theweb or film is initially subjected to a positive charge while the otherside of the web or film is initially subjected to a negative charge.Then, the first side of the web or film is subjected to a negativecharge and the other side of the web or film is subjected to a positivecharge. Such webs are produced with a relatively high charge densitywithout an attendant surface static electrical charge. The process maybe carried out by passing the web through a plurality of dispersednon-arcing electric fields which may be varied over a range depending onthe charge desired in the web. The web may be charged at a range ofabout 1 kVDC/cm to about 30 kVDC/cm or more particularly about 4 kVDC/cmto about 12 kVDC/cm and still more particularly about 7 kVDC/cm to about8 kVDC/cm.

[0059] Electret charge stability can be further enhanced by graftingpolar end groups onto the polymers of the multicomponent fibers. Inaddition, barium titanate and other polar materials may be blended withthe polymers to enhance the electret treatment. Suitable blends aredescribed in U.S. Pat. No. 6,162,535 to Turkevich et al, assigned to theassignee of this invention and in PCT Publication WO 00/00267 to Myerset al.

[0060] Other methods of electret treatment are known in the art such asthat described in U.S. Pat. No. 4,215,682 to Kubik et al, U.S. Pat. No.4,375,718 to Wadsworth, U.S. Pat. No. 4,592,815 to Nakao and U.S. Pat.No. 4,874,659 to Ando, each hereby incorporated in its entirety byreference.

[0061] Electret treatment is desirable if the cleaning sheet is to beused as a dry wiping sheet, since the charge in the cleaning sheet willtend to attract the dirt, dust and/or other debris to the cleaningsheet. In contrast, if the cleaning sheet is to be used as a wetcleaning sheet, then electret treatment is generally not desired. It ispointed out, however, that a dry wiping sheet does not have to beelectret treated and a wet cleaning sheet may be electret treated.

[0062] The multicomponent, multilobal shaped fibers of the nonwoven webused as a cleaning sheet in the present invention can optionally besplit or fibrillated. Split or fibrillated fine fibers exhibit highlydesirable properties, including textural, visual and strengthproperties. There are different known processes for producing split finefibers, and in general, split fibers are produced from multicomponentfibers which contain two or more incompatible polymer components or froman axially oriented film. For example, a known method for producingsplit fibrous structures includes the steps of forming splittablemulticomponent filaments into a fabric and then treating the fabric withan aqueous emulsion of benzyl alcohol or phenyl ethyl alcohol to splitthe multicomponent filaments. Another known method has the steps offorming splittable multicomponent filaments into a fibrous structure andthen splitting the multicomponent filaments by flexing or mechanicallyworking the filaments in the dry state or in the presence of a hotaqueous solution. Yet another commercially utilized method for producingsplit fine denier fibers is a needling process. In this process,multicomponent fibers are hydraulically or mechanically needled toseparate the different polymer components of the multicomponent fibers.Further yet another method for producing fine fibers, although it maynot be a fiber splitting process, utilizes multicomponent fibers thatcontain a solvent or water soluble polymer component. For example, afibrous structure is produced from sheath-core multicomponent fibers andthen the fibrous structure is treated with a solvent that dissolves thesheath component to produce a fibrous structure of fine denier fibers ofthe core component. For the purposes of this invention, splitmulticomponent fibers may be produced from any method which iseffective.

[0063] The nonwoven web of this invention may be produced from themulticomponent, multilobal shaped fibers alone, or in combination withother fibers, such as thermoplastic monolobal fibers. The addition ofthe monolobal fibers to the multicomponent, multilobal shaped fibershelps improves the strength of the resulting nonwoven web. The monolobalfibers can be monocomponent fibers or can be multicomponent fibers.Preferably, the monolobal fibers are multicomponent fibers made from thesame components as the multicomponent multilobal shaped fibers. As withthe multicomponent multilobal shaped fibers, a portion of the outerlayer should have a lower melting point polymer. The preferred monolobalfibers desirably have a substantially circular cross-sectional shape.

[0064] When the monolobal fibers are present in the nonwoven web, thenonwoven web cleaning sheet comprises from about 1 to about 99% byweight of the multicomponent, multilobal shaped fibers and about 99 toabout 1% of the monolobal fibers. Preferably, the nonwoven web cleaningsheet comprises from about 5 to about 95% by weight of themulticomponent, multilobal shaped fibers and about 95 to about 5% of themonolobal fibers More preferably, the nonwoven web cleaning sheetcontains from about 30 to about 75% by weight of the multicomponentmultilobal shaped fibers and about 70 to about 25% of the round shapedfibers.

[0065] The cleaning sheets of the present invention have a surface areaof at least 0.210 m²/g. Generally, the surface are generally in therange of about 0.220 m²/g to about 0.500 m²/g, and more particularly, inthe range of about 0.250 m²/g to about 0.350 m²/g.

[0066] Other fibers such as natural fibers may also be incorporated intothe thermoplastic multicomponent, multilobal shaped fibers. Examples ofsuch natural fibers include, for example, cellulosic, such as pulpfibers. The addition of natural fibers can improve the liquid absorbencyof the cleaning sheet. Various pulp fibers can be utilized including,but not limited to, thermomechanical pulp fibers, chemithermomechanicalpulp fibers, chemimechanical pulp fibers, refiner mechanical pulpfibers, stone groundwood pulp fibers, peroxide mechanical pulp fibersand so forth. If other fibers are included in the nonwoven web cleaningsheet of the present invention, these fibers should make up less than50% by weight of the nonwoven web.

[0067] Turning to FIG. 2, a process line 10 for preparing an embodimentof the present invention is disclosed. The process line 10 is arrangedto produce multicomponent continuous filaments, but it should beunderstood that the present invention comprehends nonwoven fabrics madewith multicomponent filaments having more than two components. Forexample, the fabric of the present invention can be made with filamentshaving three or four components. The process line 10 includes a pair ofextruders 12a and 12 b for separately extruding a polymer component Aand a polymer component B. Polymer component A is fed into therespective extruder 12 a from a first hopper 14 a and polymer componentB is fed into the respective extruder 12 b from a second hopper 14 b.Polymer components A and B are fed from the extruders 12 a and 12 bthrough respective polymer conduits 16 a and 16 b to a spinneret 18. Thespinneret 18 has openings arranged in one or more rows. The spinneretopenings form a downwardly extending curtain of filaments when thepolymers are extruded through the spinneret. For the purposes of thepresent invention, spinneret 18 may be arranged to form side-by-side oreccentric sheath/core multicomponent filaments, for example.

[0068] The process line 10 also includes a quench blower 20 positionedadjacent the curtain of filaments extending from the spinneret 18. Airfrom the quench air blower 20 quenches the filaments extending from thespinneret 18. The quench air can be directed from one side of thefilament curtain as shown in FIG. 2, or both sides of the filamentcurtain.

[0069] A fiber draw unit or aspirator 22 is positioned below thespinneret 18 and receives the quenched filaments. Fiber draw units oraspirators for use in melt spinning polymers are well-known as discussedabove. Suitable fiber draw units for use in the process of the presentinvention include a linear, fiber aspirator of the type shown in U.S.Pat. No. 3,802,817 or U.S. Pat. No. 4,340,563 and eductive guns of thetype shown in U.S. Pat. Nos. 3,692,618 and 3,423,266, each herebyincorporated by reference in its entirety. Generally described, thefiber draw unit 22 includes an elongate vertical passage through whichthe filaments are drawn by aspirating air entering from the sides of thepassage and flowing downwardly through the passage. A blower 24 supplieshot aspirating air to the fiber draw unit 22. The hot aspirating airdraws the filaments and ambient air through the fiber draw unit.

[0070] An endless forming surface 26 is positioned below the fiber drawunit 22 and receives the continuous filaments from the outlet opening ofthe fiber draw unit. The forming surface 26 travels around guide rollers28. A vacuum 30 positioned below the forming surface 26 where thefilaments are deposited draws the filaments against the forming surface.

[0071] The process line 10 as shown also includes a hot-air knife 34which provides a degree of integrity to the web. In addition, theprocess line includes a bonding apparatus which is a through-air bonder36. After passing through the through-air bonder, the web is passedbetween a charging wire or bar 48 and a charged roller 42 and thenbetween a second charging wire or bar 50 and roller 44. As is statedabove, the electret treatment is an optional process step and is notrequired.

[0072] Lastly, the process line 10 includes a winding roll 42 for takingup the finished fabric.

[0073] To operate the process line 10, the hoppers 14 a and 14 b arefilled with the respective polymer components A and B. Polymercomponents A and B are melted and extruded by the respective extruders12 a and 12 b through polymer conduits 16 a and 16 b and the spinneret18. Although the temperatures of the molten polymers vary depending onthe polymers used, when polypropylene and polyethylene are used ascomponents A and B respectively, the preferred temperatures of thepolymers range from about 370° to about 530° F. and preferably rangefrom 400° to about 450° F.

[0074] As the extruded filaments extend below the spinneret 18, a streamof air from the quench air blower 20 at least partially quenches thefilaments to develop a latent helical crimp in the filaments at an airtemperature of about 45° to about 90° F. and a velocity from about 100to about 400 feet per minute.

[0075] After quenching, the filaments are drawn into the verticalpassage of the fiber draw unit 22 by a flow of hot air from the heater24 through the fiber draw unit. The fiber draw unit is preferablypositioned 30 to 60 inches below the bottom of the spinneret 18. Thetemperature of the air supplied from the heater 24 is sufficient that,after some cooling due to mixing with cooler ambient air aspirated withthe filaments, the air heats the filaments to a temperature required toactivate the latent crimp. The temperature required to activate thelatent crimp of the filaments ranges from about 110° F. to a maximumtemperature less that the melting point of the lower melting componentwhich for through-air bonded materials is the second component B. Thetemperature of the air from the heater 24 and thus the temperature towhich the filaments am heated can be varied to achieve different levelsof crimp. Generally, a higher air temperature produces a higher numberof crimps. The ability to control the degree of crimp of the filamentsis a particularly advantageous feature of the present invention becauseit allows one to change the resulting density, pore size distributionand drape of the fabric by simply adjusting the temperature of the airin the fiber draw unit.

[0076] The crimped filaments are deposited through the outlet opening ofthe fiber draw unit 22 onto the traveling forming surface 26. The vacuum30 draws the filaments against the forming surface 26 to form anunbonded, nonwoven web of continuous filaments. The web is then given adegree of integrity by the hot-air knife 34 and through-air bonded inthe through-air bonder 36.

[0077] In the through-air bonder 36, air having a temperature above themelting temperature of component B and below the melting temperature ofcomponent A is directed from the hood 40, through the web, and into theperforated roller 38. Alternatively, the through-air bonder may be aflat arrangement wherein the air is directed vertically downward ontothe web. The operating conditions of the two configurations are similar,the primary difference being the geometry of the web during bonding. Thehot air melts the lower melting polymer component B and thereby formsbonds between the multicomponent filaments to integrate the web. Whenpolypropylene and polyethylene are used as polymer components A and Brespectively, the air flowing through the through-air bonder usually hasa temperature ranging from about 230° F. to about 325° F. (110° C. to162° C.) and a velocity from about 100 to about 500 feet per minute. Itshould be understood, however, that the parameters of the through-airbonder depend on factors such as the type of polymers used and thicknessof the web. The web may optionally then be passed through the chargedfield between the charging bar or wire 48 and the charging drum orroller 42 and then through a second charged field of opposite polaritycreated between charging bar or wire 50 and charging drum or roller 44.The web may be charged at a range of about 1 kVDC/cm to 30 kVDC/cm.

[0078] Lastly, the finished web is wound onto the winding roller 42 andis ready for further processing or use.

[0079] As is noted above, the HAK may be replaced with a compactingroll, however a HAK is preferred to the compacting roll for the reasonsstated above.

[0080] The cleaning sheet of this invention may be a multilayer laminateand may be formed by a number of different techniques including but notlimited to using adhesive, needle punching, ultrasonic bonding, thermalcalendering and through-air bonding. Such a multilayer laminate may bean embodiment wherein some of the layers are spunbond and some meltblownsuch as a spunbond/meltblown/spunbond (SMS) laminate as disclosed inU.S. Pat. No. 4,041,203 to Brock et al. and U.S. Pat. No. 5,169,706 toCollier, et al., each hereby incorporated by reference. The SMS laminatemay be made by sequentially depositing onto a moving conveyor belt orforming wire first a spunbond web layer, then a meltblown web layer andlast another spunbond layer and then bonding the laminate in a mannerdescribed above.

[0081] Alternatively, the three web layers may be made individually,collected in rolls and combined in a separate bonding step.

[0082] In a preferred multilayer laminate, two layers of spunbond websare joined together, with or without the meltblown layer. One of thespunbond layers is a layer of multicomponent multilobal shaped fibersand another of the layers is a layer of monolobal fibers. The layer ofmulticomponent multilobal shaped fibers gives the resulting nonwoven webthe ability to pick-up and retain dirt, dust and/or debris, and thelayer of monolobal fibers imparts strength to the laminate. Preferably,the layer of the multicomponent multilobal shaped fibers is adjacent tothe layer of monolobal fibers. It is further pointed out that the layerof monolobal fibers may be monocomponent fibers or multicomponentfibers. In addition, the layer of multicomponent, multilobal fibers mayoptionally contain other fibers described above.

[0083] In another alternative laminate structure of the presentinvention, the cleaning sheet may also have a barrier layer. The liquidbarrier layer desirably comprises a material that substantially preventsthe transmission of liquids under the pressures and chemicalenvironments associated with surface cleaning applications. Desirably,the liquid barrier layer comprises a thin, monolithic film. The filmdesirably comprises a thermoplastic polymer such as, for example,polyolefins (e.g., polypropylene and polyethylene), polycondensates(e.g., polyamides, polyesters, polycarbonates, and polyarylates),polyols, polydienes, polyurethanes, polyethers, polyacrylates,polyacetals, polyimides, cellulose esters, polystyrenes, fluoropolymersand so forth. Desirably, the film is hydrophobic. Additionally, the filmdesirably has a thickness less than about 2 mil and still more desirablybetween about 0.5 mil and about 1 mil. As a particular example, theliquid barrier layer can comprise an embossed, polyethylene film havinga thickness of approximately 1 mil.

[0084] The liquid barrier layer can be bonded together with the otherlayer or layers of the cleaning sheet to form an integrated laminatethrough the use of adhesives. In a further aspect, the layers can beattached by mechanical means such as, for example, by stitching. Stillfurther, the multiple layers can be thermally and/or ultrasonicallylaminated together to form an integrated laminate. The method of bondingis not critical to the present invention.

[0085] The size and shape of the cleaning sheet can vary with respect tothe intended application and/or end use of the same. Desirably, thecleaning sheet has a substantially rectangular shape of a size whichallows it to readily engage standard cleaning equipment or tools suchas, for example, mop heads, duster heads, brush heads and so forth. Asone particular example, in order to fit a standard mop head, thecleaning sheet may have a length of about 28 cm and a width of about 22cm. However, the particular size and/or shape of cleaning sheet can varyas needed to fit upon or otherwise conform to a specific cleaning tool.In an alternative configuration, the cleaning sheet of the presentinvention could be formed into a mitten shaped article for wiping andcleaning, which would fit over the users hand.

[0086] As indicated herein above, the cleaning sheets of the presentinvention are well suited for use with a variety of cleaning equipmentand, more particularly, is readily capable of being releasably-attachedto the head of a cleaning tool. As used herein, “releasably-attached” or“releasably-engaged” means that the sheet can be readily affixed to andthereafter readily removed from the cleaning tool. In reference to FIG.3, cleaning tool 240 can comprise handle 248, head 244 and fasteners246. Cleaning sheet 243 can be superposed with and placed against head244 such that the liquid barrier layer, if present, faces head 244. Ifthe cleaning sheet is a multilayer laminate, the side of the sheet withthe multicomponent, multilobal fibers should face away from the head.Flaps 247 can then be wrapped around head 244 and releasably-attached tohead 244 by fasteners 246, e.g. clamps. With cleaning sheet 243 affixedto head 244, cleaning tool 240 can then be used in one or more wetand/or dry cleaning operations. Thereafter, when the cleaning sheetbecomes heavily soiled or otherwise spent, the used sheet can be quicklyand easily removed and a new one put in its place. The specificconfiguration of the cleaning tool can vary in many respects. Asexamples, the size and/or shape of the handle can vary, the head can befixed or moveable (e.g. pivotable) with relation to the handle, theshape and/or size of the head can vary, etc. Further, the composition ofthe head can itself vary, as but one example the head can comprise arigid structure with or without additional padding. Further, themechanism(s) for attaching the cleaning sheet can vary and exemplarymeans of attachment include, but are not limited to, hook and loop typefasteners (e.g. VELCRO™ fasteners), clamps, snaps, buttons, flaps,cinches, low tack adhesives and so forth.

[0087] The cleaning sheets of the present invention are well suited fora variety of dry and wet cleaning operations such as: mopping floors;cleaning of dry surfaces: cleaning and drying wet surfaces such ascounters, tabletops or floors (e.g. wet surfaces resulting from spills);sterilizing and/or disinfecting surfaces by applying liquiddisinfectants; wiping down and/or cleaning appliances, machinery orequipment with liquid cleansers; rinsing surfaces or articles with wateror other diluents (e.g. to remove cleaners, oils, etc.), removing dirt,dust and/or other debris and so forth. The cleaning sheets have numeroususes as a result of its combination of physical attributes, especiallythe uptake and retention dirt, dust and/or debris. Additionally, thecleaning sheet provides a durable cleaning surface with good abrasionresistance. This combination of physical attributes is highlyadvantageous for cleaning surfaces with or without liquids such as soapand water or other common household cleaners. Further, the cleaningfabrics of the present invention are of a sufficiently low cost to allowdisposal after either a single use or a limited number of uses. Byproviding a disposable cleaning sheet it is possible to avoid problemsassociated with permanent or multi-use absorbent products such as, forexample, cross-contamination and the formation of bad odors, mildew,mold, etc.

[0088] The cleaning sheets of the present invention are also effectivein cleaning floors used for athletics, such as gym floors, indoorbasketball courts, aerobic floors and the like, which usually becomeslippery due to the presence of dust, dirt and/or other debris on thefloor, as well as liquids such as water and/or sweat. The cleaningsheets of the present invention are very effective in cleaning suchfloor surfaces since the sheet has the ability to pick-up and retaindirt, dust, debris and liquids.

[0089] The cleaning sheets can be provided dry or pre-moistened. In oneaspect, dry cleaning sheets can be provided with dry or substantiallydry cleaning or disinfecting agents coated on or in the multicomponentmultilobal fiber layer. In addition, the cleaning sheets can be providedin a pre-moistened and/or saturated condition. The wet cleaning sheetscan be maintained over time in a sealable container such as, forexample, within a bucket with an attachable lid, sealable plasticpouches or bags, canisters, jars, tubs and so forth. Desirably the wet,stacked cleaning sheets are maintained in a resealable container. Theuse of a resealable container is particularly desirable when usingvolatile liquid compositions since substantial amounts of liquid canevaporate while using the first sheets thereby leaving the remainingsheets with little or no liquid. Exemplary resealable containers anddispensers include, but are not limited to, those described in U.S. Pat.No. 4,171,047 to Doyle et al., U.S. Pat. No. 4,353,480 to McFadyen, U.S.Pat. No. 4,778,048 to Kaspar et al., U.S. Pat. No. 4,741,944 to Jacksonet al., U.S. Pat. No. 5,595,786 to McBride et al.; the entire contentsof each of the aforesaid references are incorporated herein byreference. The cleaning sheets can be incorporated or oriented in thecontainer as desired and/or folded as desired in order to improve easeof use or removal as is known in the art.

[0090] With regard to pre-moistened sheets, a selected amount of liquidis added to the container such that the cleaning sheets contain thedesired amount of liquid. Typically, the cleaning sheets are stacked andplaced in the container and the liquid subsequently added thereto. Thesheet can subsequently be used to wipe a surface as well as act as avehicle to deliver and apply cleaning liquids to a surface. Themoistened and/or saturated cleaning sheets can be used to treat varioussurfaces. As used herein “treating” surfaces is used in the broad senseand includes, but is not limited to, wiping, polishing, swabbing,cleaning, washing, disinfecting, scrubbing, scouring, sanitizing, and/orapplying active agents thereto. The amount and composition of the liquidadded to the cleaning sheets will vary with the desired applicationand/or function of the wipes. As used herein the term “liquid” includes,but is not limited to, solutions, emulsions, suspensions and so forth.Thus, liquids may comprise and/or contain one or more of the following:disinfectants; antiseptics; diluents; surfactants, such as nonionic,anionic, cationic, waxes; antimicrobial agents; sterilants; sporicides;germicides; bactericides; fungicides; virucides; protozoacides;algicides; bacteriostats; fungistats; virustats; sanitizers;antibiotics; pesticides; and so forth. Numerous cleaning compositionsand compounds are known in the art and can be used in connection withthe present invention.

[0091] The cleaning sheets of the present invention can be provided in akit form, wherein a plurality of cleaning sheets and a cleaning tool areprovided in a single package.

EXAMPLE

[0092] Cleaning sheets from multilobal multicomponent fibers wereproduced and compared to cleaning sheets produced from multicomponentround fibers and commercially available nonwoven cleaning sheets. Themultilobal multicomponent fibers were prepared using a pentalobal shapedspinneret and contain 60% by weight polypropylene and 40% by weightpolyethylene in a side-by-side configuration, using the processdisclosed in U.S. Pat. No. 5,597,645 to Pike et al, assigned to theassignee of the present application. The fibers were through-air-bondedand were electret treated. The basis weight of the resulting nonwovenweb cleaning sheet was 1.5 osy (51 gsm) and the surface area is about0.275 m²/g

[0093] The cleaning sheets from round multicomponent fibers wereprepared using a round spinnerett and contain 50% by weightpolypropylene and 50% by weight polyethylene in a side-by-sideconfiguration, using the process disclosed in U.S. Pat. No. 5,382,400 toPike et al, assigned to the assignee of the present application. Thefibers were through-air-bonded and were electret treated. The basisweight of the resulting nonwoven web cleaning sheet was 1.8 osy (61 gsm)and the surface area is about 0.219 m²/g.

[0094] The prepared cleaning sheets were compared to commerciallyavailable cleaning sheets using the following test. The Swiffer™ had asurface area of about 0.154 m²/g, the Pledge Grab-It™ had a surface areof about 0.206 m²/g and the Vileda™ Exstatic Cloth had a surface area ofabout 0.3075 m²/g. Ten samples of each sheet were compared. A trayhaving a 18″×24″ linoleum floor surface with Lexan polycarbonates sideswhich were 1.5″ high was used to test the pick-up of the cleaningsheets. A 8.5″×11″ sample of each cleaning sheet was attached to thesame mop head and handle assembly. A measured amount of debris, mixedhair clippings from a barbershop or commercially dried and packed breadcrumbs were place onto the tray. The amount of hair clipping in the eachof the 10 samples tested for each cleaning sheet ranged from 0.1 g to0.14 g and the bread crumbs ranged from 0.2 g to 0.28 g. The tray wasswept twice in the same fashion with each cleaning sheet and carefullyremoved from the cleaning implement. The amount of debris pick-up wascalculated for each sample. The results are shown in Table 1 for thehair pick-up and Table 2 for the bread crumb pick-up. As can be seenfrom the Tables below, the cleaning sheet of the present invention hasan enhanced debris pick-up as compared to the commercially availablecleaning sheets and the cleaning sheet prepared from monolobal roundfibers. It is further shown in the Tables that the pick-up of thecleaning sheets of the present invention is superior to cleaning sheetshaving smaller, larger or about the same surface area as the cleaningsheets of the present invention. TABLE 1 Cleaning Sheet Sample Average %of hair pick-up Present invention from bicomponent, 86.6% multimodalshaped fibers Comparative example from round 57.9% bicomponent fibersSwiffer ™¹ 79.0% Pledge Grab-It ™² 80.8% Vileda ® Exstatic Cloth ™³35.1%

[0095] TABLE 2 Cleaning Sheet Sample Average % of crumb pick-up Presentinvention from bicomponent, 63.4% multilobal shaped fibers Comparativeexample from round 50.5% bicomponent fibers Swiffer ™¹ 39.2% PledgeGrab-It ™² 36.1% Vileda ® Exstatic Cloth ™³   22%

[0096] While the invention has been described in detail with respect tospecific embodiments thereof, and particularly by the example describedherein, it will be apparent to those skilled in the art that variousalterations, modifications and other changes may be made withoutdeparting from the spirit and scope of the present invention. It istherefore intended that all such modifications, alterations and otherchanges be encompassed by the claims.

1. A cleaning sheet having an ability to pick-up and retain dirt, dustand/or other debris, said cleaning sheet comprising a nonwoven webcomprising a plurality of thermoplastic multicomponent, multilobalfilaments, wherein each of the filaments comprises a plurality of raisedlobal regions separated by depressed regions and the nonwoven webcomprises voids between the plurality of multilobal filaments whichallow for dirt, dust and/or other debris pick-up and retention withinthe nonwoven web.
 2. The cleaning sheet according to claim 1, whereineach multicomponent, multilobal filament comprises between 2 and 10lobes.
 3. The cleaning sheet according to claim 2, wherein eachmulticomponent, multilobal filament comprises between 2 and 5 lobes. 4.The cleaning sheet according to claim 1, wherein the thermoplasticmulticomponent, multilobal filaments comprise a thermoplastic polymerselected from the group consisting of polyolefins, polyesters,polyamides, polycarbonates, polyurethanes, polyvinylchloride,polytetrafluoroethylene, polystyrene, polylactic acid and blendsthereof.
 5. The cleaning sheet according to claim 1, wherein themulticomponent, multilobal filaments are bicomponent filamentscomprising a first polymer component and a second polymer component. 6.The cleaning sheet according to claim 5, wherein the first polymercomponent comprises polyethylene and the second polymer componentcomprises polypropylene.
 7. The cleaning sheet according to claim 6,wherein the first polymer component and the second polymer component arearranged in a side-by-side configuration.
 8. The cleaning sheetaccording to claim 1, wherein the multicomponent, multilobal filamentsare crimped.
 9. The cleaning sheet according to claim 1, wherein thebulk density of the sheet is in the range of about 0.015 g/cm³ to about0.075 g/cm³.
 10. The cleaning sheet according to claim 1, wherein thebasis weight of the sheet is between about 0.25 osy and about 25 osy.11. The cleaning sheet according to claim 10, wherein the basis weightof the sheet is between about 0.5 osy and about 10 osy.
 12. The cleaningsheet according to claim 11, wherein the basis weight of the sheet isbetween about 1.0 osy and about 5.0 osy.
 13. The cleaning sheetaccording to claim 1, wherein the nonwoven web further comprises aplurality of pulp fibers intermingled with the plurality ofmulticomponent, multilobal filaments.
 14. The cleaning sheet accordingto claim 1, wherein the nonwoven web further comprises a plurality ofmonolobal filaments intermingled with the plurality of themulticomponent, multilobal filaments.
 15. The cleaning sheet accordingto claim 14, wherein the monolobal filaments comprise a thermoplasticpolymer selected from the group consisting of polyolefins, polyesters,polyamides, polycarbonates, polyurethanes, polyvinylchloride,polytetrafluoroethylene, polystyrene, polylactic acid and blendsthereof.
 16. The cleaning sheet according to claim 15, wherein themonolobal filaments comprises monocomponent filaments, multicomponentfilaments or a mixture thereof.
 17. The cleaning sheet according toclaim 16, wherein the monolobal filaments comprise multicomponent,monolobal filaments.
 18. The cleaning sheet according to claim 17,wherein the multicomponent, monolobal filaments are bicomponentfilaments comprising a first polymer component and a second polymercomponent.
 19. The cleaning sheet according to claim 18, wherein thefirst polymer component comprises polyethylene and the second polymercomponent comprises polypropylene.
 20. The cleaning sheet according toclaim 19, wherein the first polymer component and the second polymercomponent are arranged in a side-by-side configuration.
 21. The cleaningsheet according to claim 1, wherein the nonwoven web comprises alaminate structure having at least two layers, a first layer and asecond layer, wherein the first layer comprises the plurality ofmulticomponent, multilobal filaments; and the second layer comprises aplurality of monolobal filaments.
 22. The cleaning sheet according toclaim 21, wherein the monolobal filaments comprises monocomponentfilaments, multicomponent filaments or a mixture thereof.
 23. Thecleaning sheet according to claim 22, wherein the monolobal filamentscomprise a thermoplastic polymer selected from the group consisting ofpolyolefins, polyesters, polyamides, polycarbonates, polyurethanes,polyvinylchloride, polytetrafluoroethylene, polystyrene, polylactic acidand blends thereof.
 24. The cleaning sheet according to claim 22,wherein the monolobal filaments comprise multicomponent, monolobalfilaments.
 25. The cleaning sheet according to claim 24, wherein themulticomponent filaments are bicomponent filaments comprising a firstpolymer component and a second polymer component.
 26. The cleaning sheetaccording to claim 25, wherein the first polymer component comprisespolyethylene and the second polymer component comprises polypropylene.27. The cleaning sheet according to claim 26, wherein the first polymercomponent and the second polymer component are arranged in aside-by-side configuration.
 28. The cleaning sheet according to claim 1,wherein the multicomponent, multilobal fibers comprises a higher meltingpoint polymer component, a lower melting point polymer component and aninterface between the higher melting polymer component.
 29. The cleaningsheet according to claim 1, wherein the nonwoven web is electrettreated.
 30. The cleaning sheet according to claim 14, wherein thenonwoven web is electret treated.
 31. The cleaning sheet according toclaim 21, wherein the nonwoven web is electret treated.
 32. A cleaningimplement comprising: a. a handle; b. a head; and c. a removablecleaning sheet; wherein head is connected to the handle, the removablecleaning sheet is removable attached to the head and the removablecleaning sheet comprises the cleaning sheet of claim
 1. 33. A cleaningimplement comprising: a. a handle; b. a head; and c. a removablecleaning sheet; wherein head is connected to the handle, the removablecleaning sheet is removable attached to the head and the removablecleaning sheet comprises the cleaning sheet of claim
 14. 34. A cleaningimplement comprising: a. a handle; b. a head; and c. a removablecleaning sheet; wherein head is connected to the handle, the removablecleaning sheet is removable attached to the head and the removablecleaning sheet comprises the cleaning sheet of claim
 21. 35. A method ofcleaning a surface comprising contacting and wiping the surface with thecleaning sheet of claim
 1. 36. A method of cleaning a surface comprisingcontacting and wiping the surface with the cleaning sheet of claim 14.37. A method of cleaning a surface comprising contacting and wiping thesurface with the cleaning sheet of claim
 21. 38. A cleaning kitcomprising the cleaning implement according to claim 32 and a pluralityof the cleaning sheets.
 39. The cleaning kit of claim 38, wherein thecleaning sheets are premoistened.
 40. The cleaning kit of claim 38,wherein the cleaning sheets are dry.